The inexorable trend towards cycling as a primary mode of transport for residents of urban areas and the rising cost of bicycles and their components has raised the importance of the issue of bicycle security. Bike theft is a major problem in many cities but there is a strengthening trend in ‘stripping’ bicycles of their components which are removable with common tools rather than trying to break a high security bicycle lock to remove the entire bicycle. With a very high proportion of a bicycle's value contained in its components, the issue of securing these components to the bicycle frame in a way which prevents unwanted removal is of paramount importance as with all the components secured to the frame in such fashion, securing the frame to a permanently fixed object then fully protects the cyclist's bicycle.
There are a few commercially available products for securing some of the components of a bicycle to the frame in a tamper resistant fashion. These products seek to secure components to the frame using tamper-resistant fasteners which require a specific key in order that the fastener securing the component be tightened or removed with the specific key being common to these security fasteners for all the components secured in this way on an individual bicycle but with the specific keys for a plurality of bicycles differing from one another. However, these products are inadequate in the extent of the protection they offer. Typically, these products have been developed to secure those components which are generally secured to the bicycle frame using ‘quick-release’ skewers, namely front and rear wheels and the seatpost, that is the post which inserts into the bicycle frame to which the saddle is attached at the other end. In first seeking to replace the ‘quick release’ skewers with secure fasteners, the design of these security fasteners renders them inapplicable to securing many other component parts of the bicycle as the requirements for such fasteners differ to those of the ‘quick-release’ skewers. The most obvious example of the shortcoming of currently commercially available products being contained in the paradox that while they specifically seek to provide ‘saddle security’ by securing the seatpost to the frame, the saddle itself, which can be a very expensive item, is left available to be removed by anyone so inclined who has in their possession a standard hex key. The primary reasons why existing designs of security fasteners are unable to offer a tamper-resistant method of securing components to the bicycle frame generic to the majority of components are:
i. the differing dimensions in the variety of regular fasteners used to secure components to the frame
ii. the small physical dimensions of many of these fasteners, and
iii. the fact that many of these fasteners recess into the frame or the component being secured.
There are several elements to the design of a ‘security’ fastener. The first two considerations relate to the ability of the fastener to perform its primary function i.e. that of a fastener as this requires that:
i. it is able to convert force applied to achieve the necessary torque to secure the fixture, and
ii. that the fastener and key be able to withstand repeated application of this force without a loss of material integrity.
The further elements in the design of a ‘security’ fastener are the two primary aspects in considering the security afforded a component by the security fastener. These are
iii. the degree to which the fastener can resist attempts to effect its removal using unauthorized tools, and
iv. the degree to which the specific key owned by the user for manipulation of the fasteners on their bicycle is unique.
Existing designs of fasteners are inadequate in providing sufficient security for the majority of components on a bicycle for a large number of cyclists. This is since fulfilling any one or more of the fundamental requirements results in fasteners that require physical dimensions which render them inapplicable to the general application of securing all components of high proportional value to the bicycle frame, which includes the applications requiring a small diameter fastener. Thus, there remains a need for a tamper-resistant fastening assembly capable of securing the majority of valuable components to a bicycle's frame with all such fasteners on an individual bicycle actuated by a single specific key, the specific keys for individual bicycles being different from one another. The object of the invention is to provide such a solution.
The following includes a description of prior art in the general field of security fasteners including those related to bicycle security highlighting the inadequacies of existing designs in the context of the object of this invention.
A wide variety of ‘anti-theft’, ‘tamper-proof’ or ‘security’ fasteners have been suggested to secure objects using threaded fasteners such as nut and bolt combinations with co-operating threads; the objective of the suggested designs being to prevent unwanted removal using commonly available tools. Such fasteners have two common features. The first feature commonly incorporated into such designs seeks to hamper attempts to grip the fastener with tools such as wrenches or pliers. Typically, these designs involve a smooth outer surface of a cylindrical or frusto-conical body and/or a coaxial rotating shroud external to the fastener's body. The other common feature is a design requiring a special key to enact tightening or releasing of the fastener. Suggested designs of this second key feature can broadly be categorised in six ways;
i. fasteners whose face contains a plurality of holes and/or pegs into which fit the complementary pins and/or holes of a specially designed key
ii. fasteners with a cylindrical or frusto-conical body with a single key receiving recess in the face
iii. fasteners with a cylindrical or frusto-conical body with a key-receiving groove in the face
iv. fasteners with a cylindrical or frusto-conical body with a central post located in a key receiving recess in the face
v. fasteners whose external body is not circular and is instead protected by a rotating shroud or ring and finally,
vi. fasteners with a cylindrical or frusto-conical body with a multi-tiered recess in the face.
Examples of each category of fastener are given below.
Examples of the first category of security fasteners, those whose faces contain a plurality of holes and/or pegs into which fit the complementary pins and/or holes of a specially designed key can be seen in UK patent applications 2,095,356, 2,302,575 and U.S. Pat. Nos. 954,528, 5,199,838, 5,863,166 and French patent 2,712,845. Although such designs make removal difficult, it is still possible to either rotate the nut using other tools such as adjustable in spanners, needle nose pliers etc or to modify the fastener or create a proxy key using simple commonly available tools.
An improvement on these designs which specifically relates to securing bicycle components to the frame is suggested in U.S. Pat. No. 6,341,927 which teaches a fastener with a convex head for rotation about a vertical axis. The head contains at least two cut-outs to provide two generally vertical engaging surfaces for engagement by a mating member on a specific key, one for clockwise rotation the other for counter-clockwise rotation. Interruption of the side-wall of the cut-out adjacent to the counter-clockwise engagement surface prevents counter-clockwise rotation by a tool other than the specific key. While the design is a marked improvement on other preceding designs, it will be appreciated that it is still a very quick and simple task to modify the fastener's engagement points slightly with readily available tools to enable rotation by commonly available tools such as needle nose pliers. However, the design also carries another limitation which is of far greater concern in the context of the object of this invention which is explained below.
A plethora of suggestions exist for the second category of fasteners identified based on a single key receiving recess in the face of the fastener's head. These range from those primarily designed to improve the ability to apply torque such as U.S. Pat. Nos. 5,279,190 and 5,137,407 which teach designs which ensure a high and stable conversion efficiency of torque to suggestions such as those contained in U.S. Pat. Nos. 5,378,101 and 4,618,299 which suggest multi-lobular recesses in the fastener's head to accommodate a specific mating key to effect rotation of the fastener about its axis. The weakness of any such designs in a security application is that the risk exists of an unwanted rotation of the fastener being achieved by common tools which can be forced in to the recess and adequately engage the head to apply enough torque or the minor modification of the recess to accommodate such a tool. Typically, such compromise can be achieved using standard tools such as hex keys, ‘Torx’ heads, bladed instruments etc.
The third category of designs for security fasteners suggests a fastener body which contains a key receiving groove. One advantage of such designs is that application of torque to the head is far less likely to damage the head of the fastener and so they are appropriate for high torque applications. U.S. Pat. No. 6,186,718 suggests such a fastener with a simple triangular groove for this specific purpose. However, it will be appreciated that using simple geometric designs provides a very limited range of possibilities for generating permutations for unique keys. Better examples can be seen in U.S. Pat. Nos. 4,674,306 and 5,730,567. Both teach a fastener the rotation of which about its vertical axis requires engagement by the insertion of the mating member of a specific key into a curvilinear groove in the fastener's head.
The fourth category of fasteners seeks to overcome the weakness of using modified standard tools through the positioning of a central post in the key receiving recess contained in the fastener's face. Such designs are widely commercially available and consist of a cylindrical central post within an otherwise standard key receiving recess such as a recess which fits a standard hex or ‘Torx’ key thus obstructing actuation by a standard and widely available key and also obstructing the insertion of unauthorised objects such as bladed instruments.
The fifth category of fasteners are those in which the fastener is designed so that the external wall of the central body of the threaded fastener provides the key receiving surface and is rendered inaccessible to gripping tools and thus unwanted removal by rotation using such tools by a coaxially rotating shroud or ring mounted on the central body. Such a feature is also commonplace in the design of security fasteners even when the central body is of a smooth cylindrical or frusto-conical form. Examples can be seen in U.S. Pat. Nos. 5,730,567, 4,726,723 and 4,897,008. In these designs it is an additional level of security against unwanted removal by gripping tools. However, for designs of security fasteners in which the outer surface of the body is not of cylindrical or conical form then such freely rotating shrouds are a vital element of security. A good example of such a design which specifically relates to securing bicycle components to the frame is seen in U.S. Pat. No. 5,950,506 which teaches a threaded nut of irregular periphery which is protected by a freely rotating cylindrical cap whose cylindrical wall surrounds the nut. The irregular periphery of the nut is designed such the nut can only be actuated by a specific key. The shortcoming in the context of the object of this invention is explained below.
The final category of fasteners uses a multi-tiered recess in the face of the fastener as the key-accepting engagement surface. U.S. Pat. No. 6,988,432 teaches such a design which uses tiered polygons to provide stability to a driving tool and improve the stability of the delivery of torque. U.S. Pat. No. 6,017,177 teaches a multi-tiered recessed design using a multi-lobular driving tier and irregularities in the mating surface of the other tiers. In addition to providing stability to the driving tool, the configuration of stabilizing tiers can be changed to produce an extremely large number of patterns required for a specific mating key to engage the fastener successfully. Such designs still suffer from the same weakness as the single tier recessed design in that it is possible that a bladed instrument may be inserted, possibly even across tiers, and successfully engage the fastener or alternatively, some other commonly available tool may be used to force a mating or modify the recess to achieve such a mating. Additionally, security is not a function of successful replication of three tiers but reduces to the permutations contained in a single tier as a key obtained can have the lower tier(s) ground away thus rendering any fastener with a matching upper tier vulnerable to unwanted removal.
The object of the invention is to design security fasteners which secure the majority of bicycle components to the bicycle frame and certainly all those of high proportional value which includes those components which require a small diameter fastener to secure them to the frame. This set of fasteners owned by a single individual should only be able to be actuated by the use of a single specific key which is complementary to all the fasteners on the individual's bicycle. For each other individual owning a similar set of fasteners their set should require a different specific complementary key. Thus, the main requirements of such a design are that firstly, all components of significant value can be secured to the bicycle to protect from unwanted removal and secondly, that the specific key is unique to the owner or as close to unique that the possibility of someone obtaining a replica key through legitimate means is inconceivable. Obviously this second consideration requires that the design of the security fastener can generate a very high number of permutations for unique specific keys.
The concept of using security fasteners to secure components to the bicycle frame is not new in itself and some of the preceding examples were developed with exactly this objective, notably U.S. Pat. Nos. 6,341,927 and 5,950,506, UK patents 2,095,356 and 2,302,575. However, there are major shortcomings in existing designs specifically for this objective and for the same or other reasons existing designs of security fasteners inappropriate in the context of this application.
To understand the shortcomings of existing designs for security fasteners requires an understanding of the requirements for the usual fasteners used to secure bicycle components in their normal function as simple fasteners. For some bicycle components, high levels of torque need to be applied to adequately secure the component to the frame due to the forces the component is subjected to in normal use which risk detachment of the component and the potentially dire consequences for the cyclist. For example, the rear wheel (particularly for a fixed gear bicycle) and the end bolts of square taper cranks require the fasteners to be secured using high levels of torque. The other consideration of extreme importance are the physical dimensions of the fasteners.
The different components on the bicycle require different fasteners and these frequently differ in dimension. Most importantly, a lot of components of significant proportional value require fasteners that have very small dimensions as these fasteners, typically bolts, recess into the component that they are securing to the frame or into the frame itself in their tightened position. Existing designs such as the examples referred to which have been developed for this specific application have typically been developed to secure the components to the bicycle frame which are usually secured by fasteners known as ‘quick release skewers’. These components are the wheels and the seatpost which inserts into the bicycle frame on top of which the saddle is secured. However, in the design of fasteners successful in hampering unwanted removal of these components, the general applicability of the fastener has been compromised. That is to say, the same design cannot be used to secure other valuable components of the bicycle.
A great paradox can be seen in the attempt to prevent unwanted removal of the bicycles seat. Commercially available products resulting from U.S. Pat. Nos. 6,341,927 and 5,950,506 successfully secure the seatpost to the bicycle frame yet the bicycle seat is still totally exposed to the risk of unwanted removal by anyone with a standard hex key. The problem in achieving general applicability lies in the conflicting requirements of security (tamper-resistant design and uniqueness of key), a desire to protect the components of a single user's bicycle with one key, the ability to apply adequate torque to the fastener and for the fastener to withstand this torque and the desire for minimal physical dimensions of the fastener to facilitate general application and also for aesthetic considerations.
All existing known designs are a compromise and in attaining the objectives of security (i.e. a tamper-resistant design and a reasonably high number of permutations for the possibilities for a specific key) and practical considerations as a fastener they have rendered the design inapplicable for more general application to include securing components which necessitate a fastener of small dimension. For example, the fastener taught in U.S. Pat. No. 6,341,927 is a relatively weak design from the perspective of torque application and hence requires a large enough diameter to adequately perform its function as a fastener. In so doing, it simultaneously negates the possibility of using the design to secure e.g. a seat to a seatpost in which the fastening bolt recesses into clamping mechanism used to secure the seat to the seatpost. It will be appreciated by those skilled in the art that if this design used a fastener with a smaller diameter face then it is likely that insufficient torque could be applied for the fastener to perform its function of securing safely a component to the bicycle frame and at the same time, the ability to generate a high number of permutations for specific key requirements would be lost. Similarly, to achieve adequate security U.S. Pat. No. 5,950,506 requires a separate freely rotating coaxial shroud located external to the threaded fastening nut which renders the design inapplicable to any applications requiring a small diameter fastener. The design of the nut is also relatively weak from the perspective of torque application and thus requires adequate physical dimension of the nut for the application of torque sufficient to safely secure the components as well as to permit generation of adequate specific key requirements. This results in the same set of problems as in the previous example further compounded by the use of the rotating shroud external to the nut.
Consideration of other designs of security fasteners in the context of this application also reveals inadequacies. To be clear, the object is to design a security fastening system which secures all bicycle components to the frame in which actuation of the fasteners is exclusive to a specific key common to all fasteners used on the bike and that a very high number of different permutations for the possibilities of the specific key may be produced. Thus we are considering fasteners whose external dimensions may be smaller than even 12 mm to allow recessing into components and the frame. Those skilled in the art will appreciate that designing such a fastener(s) runs into the constraints of the ability to preserve material integrity of such a fastener under repeated torque applications and constraints in the production method used e.g. the minimum diameter of appropriate cutting tools in addition to the previously stated requirements. Thus, a design such as a fastener actuated by the mating of a male member key with a curvilinear key receiving groove in the fastener's face which appears appropriate on paper is in reality inadequate in the context of the object of this invention as the material properties of the fastener and/or key and/or the minimum cutting diameter of the tool used in production drastically reduces the number of permutations that can be generated for the design of the specific key and thus compromises the security aspect of the fastener.
It is therefore an object of the present invention to provide a fastening assembly that overcomes the problems in the prior art.